1. Field of the Invention
The present invention relates to a centering apparatus of a lens supported in a lens frame which is threadedly engaged with a threaded portion formed on an inner peripheral surface of a lens barrel.
2. Description of Related Art
In a known lens barrel of a camera which is provided with, for example, front and rear lens groups which are movable relative to one another in an optical axis direction, the front lens group is held by a lens frame which is provided on an outer peripheral surface thereof with a male threaded portion (i.e., crest) which is engaged by a corresponding female threaded portion (i.e., groove) formed on an inner peripheral surface of the front end of the lens barrel. However, in such a holding structure, alignment of the center axis of the female threaded portion of the lens barrel, or the center axis of the male threaded portion of the lens frame, with the center axis (i.e., optical axis) of the lens supported by the lens frame does not necessarily ensure alignment of the optical axes of the front and rear lens groups. Various arrangements hitherto have been directed to increasing the precision of the front and rear lens group support by increasing the mechanical precision of the lens barrel. However, a direct and mechanical adjustment (i.e., centering.) of the lens frame center axis has not been proposed.